the world > movement > motion in a certain direction > going or coming in > [noun] > letting in or fact of being let in > specifically of a person to a place > one who (3)
A person who or thing which admits somebody or something (in various senses of the verb).
A person who takes someone or something in, in various senses (see to take in at take, v. phrasal verbs 1).
One who lets in or gives admittance.